Default Acro S no usb debug mode

Hello,
I am having an issue with my acro s it will not go into debug mode when connect to my pc any more, it was working fine but has just stopped. I have checked the developer options and it is selected there. I have tried in different version of Windows and no joy so I think its the phone that has the problem. I am running stock 4.1 and rooted. Please help.

Simon